Press Release

BALTIMORE, MD (August 12, 2002) --Maryland’s Departments of Health and Mental Hygiene (DHMH) and the Environment (MDE) are reminding consumers of the potential risk of eating uncooked oysters, clams, mussels and other shellfish, particularly during the warmer months of the year.

“We want everyone to enjoy fresh seafood this summer, but we also want people to be aware that eating raw shellfish can cause illness due to Vibrio bacteria,” said DHMH Secretary Dr. Georges C. Benjamin. “Shellfish should be cooked thoroughly to avoid health risks.”

Different kinds of Vibrio bacteria are found naturally in coastal waters and are not a result of pollution. Vibrio bacteria can be found in waters approved for oyster and clam harvesting. During the warm weather months more of the bacteria can be found in shellfish and the risk to consumers is higher.

“Shellfish harvested from Maryland waters have never been implicated in a Vibrio illness,” said Acting MDE Secretary Merrylin Zaw-Mon. “However, so far this year, two Marylanders have become ill after eating raw shellfish harvested out of state.”

One particular kind of Vibrio bacteria, Vibrio vulnificus, can cause serious illness or even death for people considered to be at high risk. People at "high risk" include those with liver disease, excessive alcohol intake, diabetes, AIDS or HIV infection, stomach disorders, inflammatory bowel disease, cancer, abnormal iron metabolism, steroid dependency or any illness or medical treatment which results in a compromised immune system. Older adults are more likely to have these health conditions and should be aware of their health status.

It is recommended those that are a high risk not consume raw shellfish.

People who are not at high risk can also become ill from Vibrio bacteria, although it is much less common. These bacteria can cause a gastrointestinal illness in people who eat raw or undercooked oysters or clams, regardless of age or health history.

Symptoms of illness from Vibrio bacteria include vomiting, diarrhea, stomach pains, severe weakness, skin rashes, blisters, shaking chills and high fever. If you have any of these symptoms after consuming shellfish, see your health care provider for medical treatment.

While it is rare, infection also can occur when cuts, burns or sores are exposed to seawater containing Vibrio bacteria. Avoid exposing healing wounds to saltwater when swimming or wading by covering the wound with a watertight wrap. If you get a cut or wound while in the water, clean the wound with soap and water or a disinfectant, such as hydrogen peroxide. If you notice signs of infection, such as redness or swelling, see your doctor.

Vibrio bacteria do not change the appearance, taste, or odor of oysters or clams. Eating raw oysters or clams with hot sauce or while drinking alcohol does not destroy the bacteria either. Only thoroughly cooking the oysters or clams will destroy the bacteria and eliminate the risk of infection.

For example, live oysters or clams should be boiled three to five minutes after their shells open. Using a small pot to boil or steam oysters is recommended for thorough cooking. Discard any oysters that do not open during cooking. Shucked oysters or clams should be boiled or simmered at least three minutes or until the edges curl. They may also be fried in oil for three minutes at 375 degrees, broiled three inches from the heat for three minutes or baked in a 450 degree oven for 10 minutes.

Maryland's Chesapeake Bay waters have long been known for their plentiful shellfish. To protect this valuable resource and safeguard public health, MDE is responsible for regulating shellfish harvesting waters. Shellfish include clams, oysters, and mussels. The term shellfish does not include crabs, lobsters, or shrimp. Shellfish are filter-feeding animals: they strain the surrounding water through their gills which trap and transfer food particles to their digestive tract. If the water is contaminated with disease-causing bacteria, such as Vibrio, the bacteria are also trapped and can be consumed as food.

More Vibrio and seafood safety information can be obtained by calling the U.S. Food & Drug Administration hotline at 1-(800)- 332-4010 or online from the Interstate Shellfish Sanitation Conference at: